HR: 08:45h
AN: P11F-04    [Abstracts]
TI: Solid tidal friction above a liquid water reservoir as the origin of the South Pole Hotspot on Enceladus
AU: * Tobie, G
EM: gabriel.tobie@univ-nantes.fr
AF: CNRS, University of Nantes, UFR Sciences et Techniques, 2 rue de la Houssinière BP 92208, Nantes, 44322, France
AU: Cadek, O
EM: oc@karel.troja.mff.cuni.cz
AF: Charles University, Department of Geophysics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, Prague, 180 00, Czech Republic
AU: Sotin, C
EM: christophe.sotin@univ-nantes.fr
AF: CNRS, University of Nantes, UFR Sciences et Techniques, 2 rue de la Houssinière BP 92208, Nantes, 44322, France
AB: Earth, Jupiter's moon Io and Saturn's tiny moon Enceladus are the only solid objects in the solar system to be sufficiently geologically active for their internal heat to be detected by remote sensing. But in contrast to the Earth and Io, the endogenic activity on Enceladus is only located on a specific region at the South Pole, from which jets of water vapor and ice particles have been observed. The current polar location of the thermal anomaly can be explained by diapir-induced reorientation of the satellite, but the thermal anomaly triggering and the heat power required to sustain it over geological timescales remain problematic. Using a tri-dimensional viscoelastic numerical model simulating the response of Enceladus to tidal forcing, we demonstrate that only interior models with a liquid water layer at depth can explain the observed magnitude of dissipation rate and its particular location at the South Pole. Tidal dissipation in the ice shell is large enough to explain the observed heat power and can sustain a layer of liquid water at depth over geologic timescales. Spatial and temporal fluctuations of Enceladus' gravity field to be measured by future missions should confirm the presence of the liquid water zone and its depth below the surface.
DE: 5220 Hydrothermal systems and weathering on other planets
DE: 5418 Heat flow
DE: 5422 Ices
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 5770 Tidal forces
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting